Electric cut-out



Aug.'8, 1933. E. o. SCHWEITZER 1,921,006.

ELECTRIC CUT-OUT Filed June 12, 1930 3 Sheets-Sheet 2 Patented Aug. 8,1933 UNITED STATES PATENT OFFICE 19 Claims.

This invention relates in general to circuit interrupters known as fusedcut-outs wherein a fuse is mounted in a chamber containing oil or otherinsulating liquid, although the invention is not limited to such anarrangement. A

.cut-out of this type is shown in the Patent No.

1,479,588 of January 1, 1924, granted to myself and Alfred Herz.

Briefly, this cut-out comprises a fuse link which is mounted between twocompression blocks of wood or other suitable insulating material and thewhole submerged in a bath of oil or other suitable insulating liquid.When the current flowing through the fuse becomes excessive the fuseblows to interrupt the circuit, the oil being relied upon to quicklyquench the arc that may be formed upon the blowing of the fuse.

When a fuse blows in oil it not only spoils the oil but it also coatsthe inside of the cutout and everything therein with a layer of carbonwhich is highly objectionable in that it constantly breeds trouble. Itis an object of the present invention to provide a cut-out whichovercomes this difliculty. There are two types of overload for which thecut-out renders protection. One of these types is an overload of thekind which is slightly above the capacity for which the circuit isdesigned and which is injurious only if it lasts for prolonged periodsof time, and the other is the very heavy overload of high destructivepossibilities and'which must be guarded against instantly. The formertype of overload is far more frequent than the latter and it is 'one ofthe objects of the present invention to provide a cut-out which willavoid the contamination .of the oil or other insulating liquid whenthesame interrupts a circuit upon a light overload while, at the sametime, affording protection against heavy overloads. Upon the occurrenceof a large overload the fuse blows to interrupt the circuit in the usualmanner. In order to protect the circuit against small but continuingoverloads I provide a bellows or other thermo expansive member which isadapted to be expanded by the heat generated due to the current flowthrough the circuit. When the load carried by the fuse is excessive theheat of the-fuse will expand the expansible member to'trip alcatchholding a small quick acting switch blade that is'connected in serieswith the fuse. vShould the load reach? a certain predetermined valuewhich is very much in excess of the maximum instantaneous load to becarried by the circuit the fuse will blow to immediately interrupt thecircuit without delaying until the expansible member is heatedsufficiently to bring about the tripping of the switch. The fuse may bemounted adjacent the bellows 'on the outside thereof and suitable heatconducting means may be provided to conduct the heat of the fuse to thebellows. On the other hand, the fuse may be mounted within the bellowsitself, the bellows being filled with oil,

or other insulating liquid, or it may be mounted in a small receptaclewhich communicates with the liquid within the-bellows. The bellows issubstantially filled with insulating liquid, but the liquid contentthereof should' be a small percentage of the total oil in'the tank.Thebe'llows may be filled with oil, carbon tetra-chloride, 7 0 3 ether,or the like.

Most of the oil cut-outs are employed in the protection of transformersto promptly disconnect a defective transformer so that it may notinterfere with the service of the remaining apparatus on the samecircuit. Certain apparatus which may be connected to the transformer,such as motors or the like. may take a'starting current of from two tofive times thecontinuous current carrying capacity of the transformer.In order to prevent interruption of the transformer circuits when amotor drawing such heavy current is being started it is necessary toemploy fuses whose continuous capacity is from two to five times thecapacity of the trans; 5 former. Transformers are, naturally, notdcsigned to stand even as much as a 50% overload for two or three hours,hence when an overload of 100% is connected to a transformer for anyappreciable period of time the transformer burns up since the fuseafiords no protection. 7

To avoid the destruction of a transformer upon the occurrence of such anoverload, on the theory that such overloads are unavoidable,thermometers, semaphored thermal indicators, or other indicating deviceshave been installed in each transformer and an inspector travels theline to see which transformers are running too hot. It is obvious thatthe inspector cannot be at each transformer when an .unexpected load isthrown on due to some customer failing to notify the company of his newload. Therefore, thermal indicatorscannot be relied upon to produce thedesired results'f-In addition thermal indie tors are. of themselves asource of trouble.

In my improved cut-out the switch used is "held in its closed positionby atoggle which is arranged to be tripped by the expansion of thethermo expansive member. A tripping rod extends from the togglemechanism to within a short distance of the thermo expansive member,this short distance determining the extent of permissible expansion ofthe member without producing a tripping of the switch. This same rodextends upward of the switch above the oil level' and constitutes ameans for reclosing the switch. The rod may be adjusted towards and awayfrom the expansible member in order to vary the extent of permissibleexpansion without producing an operation of the switch. A calibratedscale is provided, preferably on top of but within the oil casing, forindicating the extent of permissible expansion of the thermal element.

It is a further object of the present invention -to provide an improvedbushing structure for extending a conductor into a casing of the classdescribed. The contacts for the switch mechanism are directly supportedby the bushing structure and serve also to prevent the withdrawing ofthe circuit conductor that extends through the bushing.

In order to acquaint those skilled in the art with the manner ofconstructing and operating a device of my invention, 1 shall describe inconnection with the accompanying drawings a specific embodiment thereof,from which the attainment of the above and other objects of the presentinvention will be apparent.

In the drawings:

Figure 1 is a plan view of my improved cutout, the cover being removed;

Figure 2 is a view in partial section taken along the line 2-2 of Figue1, certain of the parts being shown in section and others being shown inelevation;

Figure 3 is a sectional view taken along the line 3-3 of Figure 2 andlooking in the direction of the arrows;

Figure 4 is a bottom view of the fuse mechanism with the bottom fusecover removed;

Figure 5 is a fragmentary sectional view of the toggle link adjustingmeans, said view being taken along the line 5-5 of Figure 2 and lookingin the direction of the arrows;

Figure 5a is a view similar to Figure 5 and showing an alternate form ofconstruction;

Figure 6 is a fragmentary sectional view of a modified form of thermalconnection between the fuse and the bellows;

Figure '7 is a fragmentary sectional view corresponding to Figure 1 andshowing a modified form of my invention;

Figure 8 is a sectional view taken along the line 8-8 of Figure 7 andlooking in the direction of the arrows; and

Figure 9 is a fragmentary end view of the op erating mechanism.

Referring now more particularly to the drawings, the cut-out comprisesan open top casing 1 which is adapted to receive the various operatingparts and which is filled with insulating oil or other insulating liquidto a level as indicated by the line 2. The casing is provided with anovel bushing structure for leading the line conductors into the casing.The bushing includes a bushing shield comprising a pair of nipples 3-4,and insulating sleeves 5 through which the conductors 6 extend. Thenipples are forced through suitable openings in the casing 1, saidnipples making a press fit within the openings. The insulating sleeve 5having the conductor 6 fitting tightly therein is itself pressed intothe nipple 4, said sleeve being pressed upward into the casing from thebottom side of the nipple. The insulator 5 is provided with a flange 6having an upper tapered surface '7 that seats against a correspondingtapered surface at the inner bottom side of the nipple and limits theextent of inward movement of the insulating sleeve 5 within thecasing 1. Since the various parts are press fitted within one anotherleakage of insulating liquid from within the casing 1 is prevented. Theconductor 6 has a portion 8 extending beyond the insulating sleeve 5,constituting means for establishing a connection with a suitableconductor for extending a circuit through the cut-out. Prior to themaking of the connection with the incoming line conductor, a guardingsleeve 10 and a clamping nut 11 are slipped over the end of theconductor and, upon the completion of the electrical connections withportion 8 of the conductor 6 the guarding sleeve is brought up to bearagainst the flange 6 of the insulator 5, said sleeve and said flangebeing both provided with co-operating tapered portions forming a conicalseat 12. The clamping nut 11 is then threaded to the bottom of thenipple 4 and, at the shoulder 13, it clamps the guarding sleeve 10 andthe insulator 5 against the nipple 4 thus effectively securing both ofthose members against outward withdrawal. A contact terminal 15 having apair of projecting ears 16 is clamped to the end of the conductor 6within the casing 1 by means of a suitable screw or bolt 17. The contact15 is tightly clamped around the conductor 6 and it rests against theinsulating sleeve 5 thereby preventing the withdrawal of the conductor 6through the sleeve and out of the casing.

Ihe top of the casing 1 is provided with an inturned circular rim orflange 18 upon which is adapted to be seated a circular disc 19 fromwhich is suspended the various operating parts, and a cover 20. A pad21, of felt or the like, is interposed between the cover 20 and theflange 18 in order to provide an effective seal to prevent the entranceof moisture or other foreign material into the casing. The cover 20 isbolted to the flange 18 by means of six bolts indicated at 22.

A block 25 of suitable insulating material is suspended from the topdisc 19 by means of four studs 26 which may be locked in place by meansof nuts 2'7. The studs 26 are threaded into corresponding holes in theblock of insulation 25 and are locked against turning, by nuts 29. Twothreaded studs 40 extend through openings in the block 25 on oppositesides of the center thereof and are locked thereto by lower nuts 41 andan upper washer 42 and an upper nut 43. The studs 40 are made of copperor other metal of high electric conductivity. Laminated spring contacts45 are mounted between the lock nut 43 and the washer 42 and are held infirm electrical contact with the stud 40 by means of the nut 43. A pivotmember 48 is welded or otherwise secured to the left hand contact spring45 and a similar member 49 is similarly secured to the right handcontact spring 45. The member 48 is pivoted between two arms gf a link51 by means of a pin 52 which extends through a circular hole in thearms of the member 51 and through a similar hole in the member 48, saidmember 48 being rotatable with respect to the arms of the link 51. Themember 49 is similarly pivoted between the two arms of a link 55 similarin construction to the link 51. The two links 51 and 55 are pivotallyconnected together by means of two pins 56 and 57 located at theopposite sides of the sets of links, said pins extending through holesin the adjacent ends of the links and screwing into a nut 58 that liesbetween the two arms of the link 51. The nut 58 comprises merely asquare block which fits between the two arms of the link 51 and which isprovided with a central opening for receiving an operating shaft in amanner to be more fully set forth as the decription. proceeds. The links51 and 55 are made of suitable electrical insulating material so as notto constitute a short circuit between the contact springs and theyconstitute a toggle for forcing the contacting ends of the springs 45into engagement with the contacts 15 mounted within the casing 1 aspreviously described. The links 51 and constitute a toggle which is ondead center when the switch is in its closed position, as illus trated,and which is forced to the open position by the action of the springpressure of the contacts 45 when the toggle is knuckled slightly upward.

An actuating or tripping rod 59 is screw threaded through an internallythreaded opening in the member 58, being locked in place by means of alock nut 60. The lock 60 may be omitted if desired. It is to be notedthat the block 58 is pivoted between the links so that it may remainhorizontal when the toggle breaks.

A block of insulating material is suspended from the studs 40, and afuse link 66 is removably mounted on the bottom side of the block 65 bymeans of a pair of screws 67. To facilitate the making of thisconnection, the block 65 is provided with a channel-shaped groove formedon its under side, in which I mount a pair of metallic plate members 68and 69 of suitable conducting material. The studs 40-40 thread intothese plates and the compression block 65 rests upon them. The screwmember 67 threads into these blocks to secure the fuse thereto and toestablish an electric circuit between the studs 4040 through the fuse.

The block 65 has a cylindrical bore formed therein at its center andextending upwardly from the bottom for a distance approximately half waythrough the block. Six small holes indicated in general at 76 aredrilled through the remaining portion of the block 65 above the end ofthe bore 75. An expansible member or chamber 78 which may be of anysuitable construction and' which in the modification herein showncomprises an expansible bellows, is mounted upon the block 65 and isprovided with a projecting stud 80 which projects through a centralopening in the block 65 and extends downwardly into physical contactwith the fuse 66. The projecting stud 80 is made of suitable heatconducting material so as to conduct heat from the fuse to the materialwithin the bellows 78.

A second compression block 86 of suitable insulating material is boltedor otherwise suitably secured to the bottom of the block 65andconstitutes a cover for thefuse. The block 86 is provided withdepressions into which the screws 67 seat and is secured to the block 65by means of two screws 87 (Figure 4) that pass into tapped holes in theblock 65. The compression block 86 is provided with a rectangular slot88 for permitting the oil or other insulating liquid within the casing lto circulate around the fuse. A cylindrical sleeve 89 of suitable heatinsulating and electrical insulating material extends between the blocks25 and 65 and surrounds the bellows, being spaced therefrom. The purposeof this sleeve is to limit the extent of circulation of the liquidwithin the casing 1 around the bellows. Thus the oil that is heatedbythe fuse rises into the space between the bellows and the sleeve andserves to effectively heat the bellows. In addition the sleeve preventsthe accidental contact between the bellows and the studs 40-40. It iswithin the purview of the present invention to omit the sleeve ifdesired.

The bottom of the actuating or tripping rod 59 extends into a. shortcylindrical bore in a fitting 90 on the top of the bellows 78. Thebottom of the rod 59 terminates a short distance from the end of thebore in the fitting 90 whereby a limited amount of expansion of thebellows is permitted without producing any effect upon the rod 59. Uponfurther expansion of the bellows the rod 59 is moved upwardly, movingthe knuckle of the toggle links 5155 upwardly to break the ,toggleandpermit the spring contacts 45 to force the switch to snap open.

An explanation will now be given of the manner of operation of myimproved circuit interrupter. When the switch is in the closed positiona circuit extends from 'the conductor 6, through the terminal contact15, through the end 91 of the right hand spring contact 45, the righthand stud 40, the fuse 66 and the left hand stud 40, thence by way ofthe left hand spring contact 45 and the left hand terminal contact 15through the conductor within the left hand bushing. The fuse 66 ispurposely made of a capacity greatly in excess of the continuous currentcapacity of the circuit in whichit is con nected, this being providedfor the purpose of permitting the starting of motors or like apparatuswhich take a starting current greatly in excess of' the normal runningcurrent. This may exceed three times the normal running current. It isapparent that a fuse of a capacity of two and one-half times the ratedcapacity of the apparatus to which it is connected will not, of itself,afford any protection against continuous overloads of say a magnitude of50%., If a smaller fuse were used then it would promptly blow upon theoccurrence of a momentary overload such as would occur upon the startingof a large motor or the like. The presentv apparatus overcomes thesedlfilCll1ti6S. Should the load current exceed the rated amount for whichthe. fuse is designed, the fuse will commence to overheat and should theoverload continue for an extended period of time the liquid adjacent thefuse will. be appreciably heated. The bulk of the heated liquid willrise and will act to heat the liquid within the bellows 78. In addition,thestud 80 which is in close proximity to the fuse link and thereforeinthe region of the hottest liquid, will conduct heat to the liquidwithin the bellows. The

bellows may be filled with oil of the same. kind as is contained withinthe casing 1, or it may be filled with any other liquid having anappreciable coeificient of expansion at the temperatures used. Carbontetra-chloride, ether, or the like may be used. Upon being heated,theliquid within the bellows will expand thereby expanding the bellows.It is to be understood that the liquid within the entire casing 1 willalso be heated but due to the construction of the cutout, as shown, thetemperature gradient will be such that the liquid in the region of thebellows will be heated sooner and to a higher temperature than will bethe rest of the body of liquid in the casing 1. Upon the expansion ofthe liquid within the bellows the top of the bellows comes intoengagement with the bottom 5 of the actuating or tripping rod 59. Uponfurther expansion of the bellows the rod 59 is moved upwardly therebymoving the knuckle of the toggle 51--55 upwardly and out of dead center.The spring contact members 45 being under stress now act through themembers 48 and 49 to force the knuckle of the toggle upwards, themembers 48 and 49 pivoting about the respective links 51 and 55 atthepins 52. The ends 91 of the contact brushes 45 thereby move out ofengagement with the terminals 15, thus breaking the circuit between theconductor 6 and the corresponding conductor in the left hand terminalbushing. It is to be noted that the tripping of the switch is dependentupon the expansion of the liquid within the bellows 78 which expansionis not dependent upon the existence of a temperature difference betweenthe liquid within the bellows and that outside of the bellows. Thus,even if there should be a circulation of the liquid outside of thebellows, that is the liquid within the casing 1, the switch wouldneverthelessbe tripped upon the occurrence of a continuing overload.When the switch trips, the plunger 59 is moved upwardly, said plungerextending through an opening in the top 20 of casing and into a sleeve92 which is closed at its outermost end is threaded into the covermember 20.

To reset the switch, the cap portion 92 is unscrewed and the operatingrod or plunger 59 is pushed downwardly. This forces the contactsprings45 back into engagement with the contact 15 thereby assuming theposition shown in full lines in Figure 1. In order to limit the extentof downward motion of the knuckle of the toggle comprising the links51--55, one of the links 55 is extended beyond the knuckle as indicatedat 55 and is provided with an extended portion 55a whichengages the pin52 when the links 55 and 51 reach a position of alignment. For thispurpose the pin 52 ,is extended beyond merely necessary to depress theoperating rod 59 downwardly as far as it will go in order to bring theswitch into its full closed position.

Fromthe description thus far given it is apparent that the distancebetween the bottom of the tripping rod 59 and the bellows 78 when theswitch is closed will determine the extent of permissible expansion ofthe bellows without operating the switch. In order to vary the extent ofpermissible operation of the bellows the rod 59 may be adjustedlengthwise of the member 58 to bring the bottom of the rod closer to orfurther away from the bellows. This may be accomplished by loosening thelock nut (Figure 5), if such a nut is provided, and then rotating therod 59 to lower it. The disc 19 is calibrated as indicated'at 95 and apointer 96is mounted upon the operating rod 59 so that upon turning ofthe operating rod to advance the rod towards or away from the bellowsthe pointer 96 moves across the calibrated scale 95 to indicate theextent of permissible operation of the bellows. The pointer 96 ispreferably mounted upon the rod 59 so as to be freely slidable withrespect thereto to a'limited extent but it is nonrotatable with respectto the rod 59. This may be accomplished by making the rod 59 square 75at its end. This will permit the free rising of the link 51 at one endthereof. It is thus the operating rod 59 when the switch is tripped.When the operating rod rises due to the tripping of the switchthepointer96 may be held against rising by engagement thereof with the cover 20.It is, of course, to be understood that any other desirable arrangementmay be provided for indicating the extent of turning of the rod 59 andthereby indicating the extent to which the rod has been advanced towardsor withdrawn from the bellows. As an alternative arrangement the centralopening in the block member 58 need not be internally threaded. The rod59 extends freely through the opening and is held in place by means of apair of lock nuts 60--60 as shown in Figure 5a. In such an arrangementit is necessary to withdraw the operating mechanism from within thecasing 1 in order to adjust the rod 59 to vary the extent of permissibleoperation of the bellows 78.

Should an exceedingly heavy overload such as a short circuit or the likeoccur upon a line which is being protected by my improved cutout thenthe circuit will be interrupted instantly by the blowing of the fuse.This is necessary because under such circumstances it would be poorpractice to permit the short circuit to continue until the liquid withinthe bellows '78 has heated sufficiently to cause the tripping of theswitch. To replace the fuse the entire mechanism must be removed fromthe casing 1. This may be accomplished by first removing the cover 20and then lifting the disc 19 outwardly. Upon the removal of the disc 19the studs 26 are likewise removed since the studs rest within the discand removal of one brings about the removal of 110 the other. The entiremechanism is thus lifted out of the casing by the lifting therefrom ofthe disc 19. It is to be noted that the diameter of the block 25 and thediameter of the block 65 is such as to permit their withdrawal past the115 contacts 15-15 and throughthe opening in the flange 18 of thecasing. The casing is provided with a drain plug 94 permitting drainingof the oil or other insulating liquid within the casingthereby-permitting the cleaning of the casing 120 and the replacement ofthe oil therein by fresh oil whenever necessary. a

As a modification of the above described structure I propose to mountthe fuse 66 within a casing 101, of glass or the like, and connected incircuit in the same manner as is the fuse shown in Figure 2. Themodification is shown in Figure 6. In this form of my invention the studis made in the form of a tube or the like establishing communicationbetween the inside of the bellows 78 and the inside of the casing 101.In this arrangement the bellows and the casing 101 maybe filled withoil, carbon tetrachloride, ether, or any other suitable insulatingliquid which preferably has a high coefllcient of 135 expansion. In thisarrangement, upon the occurrence of a slight but continuing overload,the heat generated by the fuse heats the liquid within the casing 101and within the bellows 78, since the two are in communication, thusexpanding the bellows to bring about the operation of the switch. Uponthe occurrence of a greater overload the fuse will blow, but if theoverload is not too severe the glass 101 will not be shattered hence thearc of the fuse will be quenched 145 by the liquid in the tube 101 whichis of greater insulating quality than the oil. If the arc is not quicklyquenched, the gases generated by the arc may cause an expansion of thebellows to trip the switch, thus insuring the interruption of thecircuit without the contaminating of the oil in the casing 1. verysevere overload the glass 101 will be shattered thus rendering the oilor other insulating liquid within the casing 1 available for quenchingthe are produced by the blowing. of the fuse. In addition, it is to benoted that the liquid within the bellows is under a certain amount ofpressure due to the elasticity of the bellows itself, hence when thefuse blows the bellows will tend to collapse and force the carbontetrachloride directly into the region of the are withv a certain amountof force' thereby tending to quickly quench the are. This isadvantageous for two reasons. First, due to the velocity of the liquidissuing from the member SOthere will constant- Upon the occurrence of afreely rotatable. A -coiled thermal spring mem- 1y be fresh coolingliquid within the regionof the are tending to quickly cool thesame.Secondly, the carbon tetra-chloride or the ether has higher insulatingproperties than the surrounding oil. The addition, due to theirlowboiling point, they will quickly vaporize and, by extracting the heatnecessary to vaporize them',,

namelythe heat of vaporization, they will additio'nally 'cool the regionof the arc and thus tend to quickerv extinguish. thesame.

Themember ber 1285 which is of a construction substantially identical tothe spring 128a, is secured tothe opposite end of the shaft 130. Theouter end 127 of this last mentioned thermal spring rests upon a copper,block 135 which is secured to the upperside of the compression block 65.A bolt 136, "of copper or'the like,.extends through. a

perforated opening in the end of the thermal spring 128b, s'aid'boltextending through the block 135 and through the compression block andbeing threaded into aiblock ,69 of-copper that is secured to the lowerside of the compression block65. This copper block 69 corresponds infunction to the block 69 shown in Figures 2 and 4. The insulating stud.40 extends through thefcom'pression block 65 and is threaded into asuitable threaded opening in the copper block has the effect of a nozzlewhich is directed into the region of the arc to quench the are byablowoutand a cooling action. The bellows with the insulating liquidtherein is thus of use in the case of a slight but continuing shortcircuit in that the expansion thereof causes a tripping. of the toggleswitch, and it is of use.

69 thus supporting the block 69 and thecompres sion block 65 which reststhereon. A fuse 66 is mounted. on,the bottom side of the -compressionblock 65 in the same manner, asismounted the fuse 66 of Figure2,previouslydescribed.

A compression block 86' similarto the corresponding block in the cut-outpreviously described during a very severe short circuit in that it tendsto project the liquid from the bellows into the region of the arc toquickly and effectively quench the are. I g

It is well known that he, insulatingliquid has lower arc quenchingproperties than the same liquid has when cold. Now, when a severe ismounted'upon the lower side of the compression block 65 said formerblock being provided with a rectangular opening 88 therein forpermitting oil or other insulating liquid within the casing 1 tocirculate around the fuse'link. The

vblock 65 is provided with a-central hole 140 and overload is precededby a slight overload of an' extended duration the liquid ejected throughthe tube 80 is quite hot due to the previous heating of the same. Tomake up for the decrease in the are quenching ability of the liquid, theliquid is ejected through the region of the are at a greater velocitydue to the fact that the hot liquid has expanded thebellows which nowerts a greater pressure upon the liquid.

Reference may now be had more particularly to'Figures 7, 8 and 9 whereinI show a modified form of my improvedcircuit interrupter. In this formof interrupter the block 65 is mechanically supported from the block 25by means o f two studs 40 and 40'. The stud 40 is made of copper orothersuitable conducting material and -is electrically and mechanicallyconnected in the a plurality of spaced holes 141 extending therethroughimmediately above the fuse link. Oil that isheated by v the fuse linkmayrise through these openingsinto the space between .the blocks 25. and 65and act to heat the thermal expansion springs 128a and 1282). This is inaddition to the heating efiect upon these springs of the current flowing through them. If desired a shield membercorresponding to the member89 in the cut-out previously described may be hereprovided for confiningthe heated oil within the region of the thermal expansion members 128aand 1282), although this is not indispensable.

Theshaft 59-for tripping the toggle switch extends to within a; shortdistance of the rotatable same manner as is the stud 40 at the righthand side of Figure 2. The stud 40', on the other hand. is made ofinsulating material and'is mechanically mounted in substantially the.same

manner as is the stud 40. A washer 42 of copper or other suitableconducting material is inter-- posed between the, block 25 and the nut43 that clamps the springs 45 in place. This washer extends the electriccircuit from the left hand spring 45 to a stud 125 of copper or the likethat extends through the block 25 and is threaded into a block 126 whichis mounted upon the compression block .65 on the upper side thereof.

The end 127 of a coiled thermo expansion spring.

128a rests upon the copper block 126 and is provided with a perforationthrough which the stud- 125 extends, said stud being locked to the block126 and to the end 127 of the thermal element membe1y 13 0 and this lastmentioned member is providedwith a cam 145 which is keyed theretoimmediately below theqbottom of the shaft 59. This cam member may takethe form of a rectangular block. or the like. Upon rotation of theshaftmember 130 the cam 145 forces the operatingrod59 upwardly tobreakthetoggle formed by the links 51 and 55 of the toggle switch therebypermitting the spring contact 45 to trip.-,

The circuit forthe cut-out extends from the right hand contact 15,through the right hand spring contact 45. and the stud 40 to the block68, thence by way. of the fuse 66 and the block 69". to the stud 136and. the thermal spring 1281). Thence thecircuit extends by wayof theshaft 130 to the thermal spring 128a and the block 126. From. the block126 the circuit extends through. thecopper stud 125 to thewasher 42 andthence to the left-hand contact spring 45 andthe left hand contact 15.Should-an excessive current flow through the cut-out for prolongedperiods of time the thermal expanexcessive current flowing through thefuse 66 since the heated oil in contact with the fuse rises through thecentral opening 140 and the spaced openings 141. The thermal expansionsprings upon being heated tend to uncoil and thereby rotate the shaft130 through a limited angle. This produces a rotation of the cam 145bringing this cam into engagement with the operating-rod 59. Uponfurther rotation of the shaft 130 the cam forces the operating rod 59upwardly to trip the switch in the manner previously set forth; Upon theoccurrence of' a very large overload the fuse 66 willblow instantly toimmediately interrupt the circuit without waiting-for the heating of thethermal expansion members.

In compliance with, the requirements of the patent statutes I haveherein shown and described a few"preferred embodiments of my invention.It is, however, to be understood that the invention is not limited tothe precise construction of the embodiments herein shown but is capableof modification, the embodiments herein'shownbeing merely illustrativeof the principles of my invention. What I consider new and desire tosecure by Letters Patent is:

1. A switch comprising a pair of stationary contacts, apair of springcontacts adapted to engage the stationary contacts, a toggle formaintaining the contacts in engagement, said toggle being substantiallyon dead center and maintaining the spring contacts under stress when theswitch is closed, means for breaking the tog-' gle, whereby the stresson the spring contacts is released and the contacts snap away from the,stationary contacts to open the circuit, and thermal means for actuatingsaid last named means, said first means including means for varying thedistance to the'thermal means for varying the point of operation of theswitch.

' 2. A'switch comprising a pair of stationary contacts, a pair of springcontacts adapted to engage the stationary contacts, a toggle formaintaining the contacts in engagement, said toggle being substantiallyon dead center and maintaining the spring contacts under stress when theswitch is closed, means comprising a memberextending through the togglefor breaking the-toggle, whereby the stress on the spring contacts isreleased and the contacts snap away from the stationary contacts toopenthe circuit, and thermal expansion means including an electric fusefor actuating said last named means,. said first named means beingadjustable towards and away from the thermal means whereby the point ofoperation of the toggle is. altered.

3. An electric switch including a casing, a switchxclosing and openingrod extending from the casing to the outside thereof, and movable meansspaced from the end of the rod within the casing and movable intoengagement therewith for tripping the switch, said rod being adjustabletowards and away from the movable means for altering the extent ofpermissible movement of the movable means before the same actuates thetripping rod.

4. An electric switch including a casing, a switch closing and openingrod extending from the casing to the outside thereof, a removable capmember secured to the casing and enclosing the end of the rod, andmovable means spaced from the end of the rod within the casing andmovable into engagement therewith for tripping the switch, saidrod beingadjustable towards and away from the movable means for altering 'thecontacts, and means for tripping the contact making members out ofengagement with the contacts, and a removable cover independent of theswitching mechanism for covering the casing and preventing removal ofthe switching mechanism from the casing.

'6; An electric switch including a casing, a bushing extending anincoming conductor into the casingfa switch contact mounted on andsupported by the bushing structure, and a removable switching mechanisminserted into the casing and including a contact'making member adaptedto engage the contact, said mechanism including means operable while themechanism is within -the casing 'for snapping the contact making memberout of engagement with the contact to interrupt the circuit.

7. An electric switch including a casing, a bushing extending anincoming conductor into the casing, a switch contact mounted on andsupported by the bushing structure, and a removable switching mechanisminserted into the casing and including a contact making member adaptedto engage the contact; said contact making member being held inengagement with the contact against spring tension urging it away fromthe contact, said mechanism including means for holding the contactmaking member in engagement with the contact and means for releasing thesame.

8. A cut-out mechanism comprising a mounting ring member, a pair ofblocks suspended from the mounting ring member, a switch mechanismmounted on one 'of the blocks, a thermal element mounted on the otherblock, switch tripping means extending into the region of the thermalmeans and spaced therefrom so that upon a predetermined expansion of thethermal means the switching means is tripped open, and means extendingthrough the ring member for varying the spacing between the trippingmeans and the thermal means.

9. A switch including a toggle mechanism, spring means for urging thetoggle to theopen position, a shaft extending through the knuckle of thetoggle for actuating the same to the closed position against the actionof the spring and for initiating the switch opening movement of thetoggle, an expansible element spaced from one the toggle, the positionof said shaft in the toggle within the casing, and means including adischarge passageway for ejecting fluid from the first mentioned meansinto the. large casing through the region of the are upon theinterruption of the circuit.

11. A circuit interrupter comprising two chambers containing 'arcquenching liquid and communicating with one another through a restrictedopening, means in one of the chambers for interrupting a circuit anddrawing an are adjacent the opening, the liquid in the other chamberbeing ejected through the opening into the region of the arc upon theopening of the circuit at the circuit interrupting means.

12. In combination, a fragile casing. a fuse therein adapted to breakthe casing upon blowing of the fuse, a second casing containing arcquenching liquid under pressure and communicating with the firstmentioned casing at the point of arc formation by the fuse, whereby theliquid from the second casing flows through the region of the are uponbreaking of the fragile casing thereby serving to quench the arc.

13. In combination, circuit interrupting means and a bellows containingarc quenching liquid and having an opening directed into the region ofthe are formed by the circuit interrupting means.

14. In combination, a casing, circuit interrupting means therein, acontractible member within the casing, said member containing arcquenching liquid and having an opening .directed into the region of theare formed by the circuit interrupting means, and a bath of insulatingliquid submerging the contractible member and the circuit interruptingmeans.

15. A circuit interrupter comprising af'switch, a thermal element and afuse in series, said fuse being adapted to heat the thermal element,

and means actuated by the thermal element for opening the switch.

16. Circuit interrupting means including an electrothermal element and afuse connected in series and immersed in a bath of insulating liquid.

1'7. Circuit interrupting means including an electrothermal element anda fuse connected in series and mounted to facilitate a heat exchangebetween them, said fuse and thermal element being immersed in a bath ofinsulating liquid.

18. In combination, a toggle switch, a fuse, and a thermal expansionelement connected in series, said fuse and said thermal element, beingin heat exchange relation, and means controlled by the thermal elementfor trippingthe toggle of the switch, said thermal expansion element andsaid toggle switch being immersed in a bath of insulating liquid.

19. A block of insulation having a fuse mounted on one side thereof, anda thermal element mounted on the other side thereof and electricallyconnected in series with the fuse, said block being arranged tofacilitate a heat transfer from the fuse to the thermal element.

EDMUND 0. SCHWEITZER.

